The Roles of Human Gut Inhabitants in Infant Development

By Maryna Mullerman ’20

Figure 1. Gut microbiota changes are crucial for the healthy development of infants.

Farzana Yasmin and researchers from the University of Alberta in Canada analyzed how microbial systems in infant guts change over time, as well as how they can be affected by perinatal factors such as antibiotics, formula feeding, and birth mode. The study would reveal the importance of tracking variations in microbial community during early life stages.

The researchers collected data from 166 infants from the Canadian Healthy Infant Longitudinal Development (CHILD) cohort. The study compared the microbial composition in fecal samples at different stages of infant development, with operational taxonomic unit (OTU) being used to measure microbe quantities. The infant data was split into seven mutually exclusive groups based on how the infants were delivered and fed, as well as whether they were exposed to postnatal antibiotics. Significant analysis of microarrays (SAM) was used to determine OTU changes. The study’s standard was a group of infants who were vaginally delivered, breast-fed, and not exposed to antibiotics.

SAM magnitudes were used to describe the OTU changes. The study explored many bacteria species, including Enterobacteriaceae bacteria and Ruminococcaceae bacteria, that were thought to be relevant to infant development. The standard group showed a significant increase in lactate producers and lactate utilizers, both of which were important for metabolic activity and food allergy prevention. Formula-fed infants showed unchanged abundances of Enterobacteriaceae bacteria, which previously correlated with increased food sensitization risks. In vaginally born, formula-fed infants, unchanged Ruminococcaceae levels helped with maintaining the microbiota-mucin barrier, believed to protect the gastrointestinal tract. Overall, the SAM method revealed that cesarean section-born formula-fed infants experienced the fewest microbial abundance changes.

The researchers acknowledged numerous limitations of the study, such as the inability to test the independence of one factor over another. This prevented the researchers from showing direct correlations between changes in microbiota and specific perinatal factors. The study assessed the gut microbial composition in infants to verify the importance of assessing taxon changes. The study successfully identified important bacterial communities. However, more research is needed to understand how the normal gut microbial environment operates in infancy, as well as how specific deviations might affect an individual’s development.